1. Field of the Invention
The present invention relates to a light emitting diode (LED) package having a dual lens structure and a liquid crystal display (LCD) device implementing the same, and particularly, to an LCD device in which an array of low power LEDs having a compound dual lens structure are configured for advantageous application in a backlight module of low power so as to increase the optical efficiency and enhance the brightness.
2. Discussion of the Related Art
In general, a direct-type backlight used for a large size liquid crystal display model is configured to reflect light emitted from cold cathode fluorescent lamps on a reflecting plate to provide illumination to a liquid crystal panel disposed at a front surface thereof. Here, a diffusing sheet is additionally disposed in a light reflection path such that light can be locally emitted with a uniform luminance onto the LCD panel. However, such type of backlight becomes thicker, which causes the LCD device to become more complicated and bulky in its configuration and to become larger in its size.
Recently, as a surface light source which emits light only when current passes therethrough, a light emitting diode (LED) having characteristics such as a rapid response speed, low power consumption, a semi-permanent lifespan and the like, is utilized to thusly implement a thinner backlight and simultaneously enhance the brightness thereof. Above all, as compared with the existing cold cathode fluorescent lamps, the LED can present more natural colors and images with higher quality. Also, the LED can solve the problem of after-image for moving images and can be recognized as an environment-friendly product not using mercury. As a result, it can be employed as a core component of a next generation LCD so as to replace the cold cathode fluorescent lamp.
Hereinafter, a direct-type LED backlight of an LCD device according to the related art will be briefly described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of an LCD device having a direct-type LED backlight device, and FIG. 2 is a plan view showing a plurality of PCBs (Printed Circuit Boards) fixedly arranged onto a lower cover of the LCD device in FIG. 1.
In the LCD device as shown in FIG. 1, a backlight unit is provided on a lower cover 30 disposed at a lower side of a main support frame 50 formed of molded resin or stainless steel (SUS STEEL) to have a square shape, and a liquid crystal panel 10 is stacked above the main support frame 50. An upper cover 60 encloses the edges of a front surface of the liquid crystal panel 10 and is assembled with the main support frame 50 and the lower cover 30.
The liquid crystal panel 10 includes a thin film transistor array on a substrate and a color filter substrate bonded together, and liquid crystal interposed therebetween.
As shown in FIGS. 1 and 2, the backlight unit for applying light onto the liquid crystal panel 10 includes an LED array 36 configured such that red, green and blue color (R, G and B) LED packages each of which includes a cluster of R, G and B LED chips for emitting light are linearly arranged along respective ones of a plurality of PCBs (Printed Circuit Boards) 34 disposed on the lower cover 30. A reflecting plate 32 is disposed on the entire lower surface at a region, in which the PCBs 34 are driven, for reflecting light. A diffusing plate 42 is disposed above the LED arrays 36 for diffusing light emitted from the LED arrays 36, and a prism sheet 44 is used in order to increase the luminous intensity of the light by refracting the light diffused by the diffusing plate 42. And a protection sheet 46 is disposed for protecting the prism sheet 44.
As such, the light emitted from the R, G and B LED chips composing each cluster is mixed together so as to generate white light. The white light is emitted to the outside of each cluster. Such emitted light is usually converged on a central portion of each cluster according to the emission characteristics related to the LED chip fabrication and the like.
However, such an arrangement in the related art backlight unit results in dimness and non-uniformity in the overall brightness of the backlight unit, and consequently a great number of such LEDs must be employed in order to obtain sufficient illumination, increasing the cost, power consumption and heat.